Monday, April 21, 2008

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 210516
SWODY2
SPC AC 210514

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1214 AM CDT MON APR 21 2008

VALID 221200Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

SHORTWAVE TROUGH WILL EJECT NE THROUGH THE UPPER MS VALLEY AND UPPER
GREAT LAKES TUESDAY. THIS FEATURE WILL PROVIDE IMPETUS FOR ATTENDANT
COLD FRONT TO CONTINUE EAST THROUGH THE GREAT LAKES AND OH VALLEY.
TRAILING PORTION OF FRONT WILL MOVE SWD INTO THE LOWER MS VALLEY AND
TX WHERE IT WILL LIKELY STALL BEFORE BEGINNING TO MOVE BACK NWD AS A
WARM FRONT TUESDAY NIGHT. AN UPPER RIDGE WILL BUILD OVER THE SRN
PLAINS AND LOWER MS VALLEY IN WAKE OF SHORTWAVE TROUGH MOVING INTO
THE UPPER GREAT LAKES. THE DRYLINE WILL LIKELY RETREAT WWD INTO WRN
TX TUESDAY NIGHT AS SSELY LOW LEVEL JET STRENGTHENS IN RESPONSE TO
HEIGHT FALLS RESULTING FROM UPPER TROUGH ADVANCING THROUGH THE WRN
U.S. AND NRN MEXICO.


...MID MS VALLEY THROUGH SRN PLAINS...

SCATTERED THUNDERSTORMS WILL LIKELY BE ONGOING ALONG AND JUST AHEAD
OF COLD FRONT FROM THE UPPER MS VALLEY AND GREAT LAKES SWWD THROUGH
THE MID-LOWER MS VALLEY AND ERN OK. THIS ACTIVITY MAY POSE A THREAT
FOR MAINLY HAIL. WITH RICH LOW LEVEL MOISTURE IN PLACE BENEATH STEEP
MID LEVEL LAPSE RATES...THE WARM SECTOR SOUTH OF THE FRONT WILL
LIKELY BECOME QUITE UNSTABLE...MAINLY OVER PARTS OF TX AS THE
BOUNDARY LAYER WARMS DURING THE AFTERNOON. SCATTERED STORMS WILL
LIKELY CONTINUE DEVELOPING OVER THE LOWER-MID MS VALLEY REGIONS
WHERE CAP MAY BE WEAKER ALONG ERN PERIPHERY OF THE EML. THIS
ACTIVITY MAY POSE A THREAT FOR ISOLATED DAMAGING WIND AND HAIL.
HOWEVER...DEEP LAYER WIND AND VERTICAL SHEAR PROFILES WILL LIKELY
WEAKEN AS THE UPPER RIDGE BUILDS DURING THE DAY. THERE IS ALSO
CONCERN THAT ONGOING PRECIPITATION AND CLOUDS MIGHT LIMIT
DESTABILIZATION POTENTIAL OVER THE MID-LOWER MS VALLEY.

FARTHER WEST ACROSS SRN OK AND TX...WEAK FRONTAL CONVERGENCE...
STRONG CAP AND BUILDING RIDGE WILL PROBABLY LIMIT THUNDERSTORM
DEVELOPMENT DURING THE DAY. IF ISOLATED STORMS DO MANAGE TO
DEVELOP...THE THERMODYNAMIC ENVIRONMENT WOULD SUPPORT A SEVERE
THREAT WITH LARGE HAIL AND ISOLATED DAMAGING WIND POSSIBLE DESPITE
MODEST VERTICAL SHEAR PROFILES.

OVERNIGHT...OTHER STORMS MAY DEVELOP LATE FROM NWRN TX INTO OK
WITHIN ZONE OF INCREASING LIFT AND DESTABILIZATION NORTH OF THE
FRONT...AUGMENTED BY THE DEVELOPING SLY LOW LEVEL JET. ISOLATED
LARGE HAIL WILL BE THE MAIN THREAT WITH THIS ACTIVITY.

WILL MAINTAIN 5% SEVERE PROBABILITIES GIVEN THE CONDITIONAL NATURE
OF THE THREAT IN THESE AREAS.

..DIAL.. 04/21/2008

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